1. Field of the Invention
The present invention relates to a scanning probe microscope (spm) with improved Z rough movement control for preventing electrification on a measurement sample and for providing high precision measurement.
2. Background Information
A conventional Z rough movement mechanism for a scanning probe microscope has a mechanical mechanism using a contraction lever or mechanism in which an actuation screw is driven by a pulse motor. Furthermore, end detection in Z rough movement feed has been made by detecting a deflection amount of the cantilever or a time point at which the vibration amplitude attenuation exceeds a set value. Also, prevention against electrification on a sample surface has been made by neutralizing charges by previously radiating ion spray to a sample surface or releasing the sample surface charges by using a conductive cantilever.
In the conventional scanning probe microscope, a fine cantilever with a probe needle is mechanically scanned using a piezoelectric scanner to make information of a cantilever deflection amount into an image. Here, when the cantilever is approached to a sample surface (Z movement), a probe needle tip is liable to be broken due to snap-in when the cantilever is drawn due to a sample surface force, electrostatic force electrified on the sample surface or the like. Furthermore, if the cantilever is approached to a sample surface at high speed, the probe needle tip or, as the case may be, the cantilever itself is broken by impact due to contact with the sample surface. That is, there has been a problem that Z rough movement is impossible to perform. Further, for an insulation sample with electrification nature, there has been cases that charges ar accumulated on a sample surface by friction between a sample and a probe needle due to scanning of the probe needle even during measurement with a result that measurement is impossible to be performed in a stable manner.
In order to solve the foregoing problems in the conventional art, the present invention is structured to have, in a cantilever section, a plurality of measurement and conductive Z distance control cantilevers. In the present invention, the Z distance control cantilever is soft with a spring constant of 0.01-0.1 N/m and round with a tip diameter of 100-200 nm, thereby providing a structure which is not damaged even if brought into contact with the sample surface at high speed. Furthermore, Z rough movement control is switched by a deflection signal of the Z distance control cantilever to provide a structure in which the measurement cantilever is slowly fed to a sample surface vicinity.